Broadcasting RTCM-Data for MSRTK Modules

Overview

The following article explains different ways to get correction data from your RTCM Base Station to the ANavS® MSRTK-Module. Depending on your application choose the way you want to broadcast the RTCM data to your rovers (MSRTK Modules). As broadcasting already says, one RTCM Base Station can deliver multiple rovers with RTCM correction data.

Content

Broadcast RTCM-Data per WiFi

Range: Depending on used WiFi-Antennas. With standard-setup roughly 100 meters.

The following describtion shows broadcasting correction data over the own RTCM Wifi-network with SSID=ANavS_RTCM_service. For receiving the correction data, which are mandatory for RTK-Positioning, the WiFi-Setup of your MSRTK Module have to be adjusted to connect with the RTCM Base Station Wifi-network.

Step 1: Toggle the WiFi-Modus of your MSRTK-Module from AP-Mode to normal Mode, where MSRTK Module is connecting to the listet (known) SSID-Networks. Here the MSRTK-Module should connect to the SSID=ANavS_RTCM_service (Password: anavsrtk) . Figure 1 shows the corresponding step in the Wizard. Please restart your MSRTK Module and keep it in the near of the RTCM Base Station.

Figure 1: Changing WLAN-Mode to connect with RTCM-Station

Step 2: Now you have to find out the assigned IP-address to the MSRTK-Module in the connected network of the RTCM Base Station. For this, please connect also your PC/Laptop to the network of the RTCM Base Station (SSID=ANavS_RTCM_service) .

Step 3: Now scan on your Laptop/PC the network for the IP address of the MSRTK Module with a proper scanning tool (e.g. nmap, explained in the article Using the IP scanning-tool NMAP). For this, scan the network for the entire sub-IP space of the network to which your MSRTK Module is connected with nmap -sn 192.168.43.0/24

Step 4: Note the detected IP-address of your MSRTK-Module. But be aware, don’t take the IP-Address of your Laptop/PC or of the RTCM Base Station itself.

The IP-address of the RTCM Base Station is 192.168.43.1

The IP-address of your laptop can be found in the command-line with the instruction ifconfig (Linux-OS) or ipconfig (Windows-OS)

Step 5: Navigate on your Laptop/PC to …/ANavS_RTK_Wizard/ANavS_PAD/configs and open the file ip_table.conf

Step 6: Change the IP-address of the MSRTK-Module with the line-beginning IP_MSRTK_module to the one found by the network-scan

Step 7: Start the ANavS® Wizard and continue with the settings of the sensorfusion to start it.

Broadcast RTCM-Data per Internet over own Router (Port-Forwarding)

Range: only limited by your local mobile-network connection

The following describtion shows broadcasting correction data over the Internet. For receiving the correction data, which are mandatory for RTK-Positioning, the MSRTK Module must be connected per mobile-network (e.g. LTE) to the internet. For this, the MSRTK Module has already a LTE-Module integrated.

Step 1: Connecting the ANavS® RTCM Base Station with your router per ethernet cable makes it accessable over the internet (requirement: router is also connected to the internet). To get correction data outside or inside of your network, you have to do the next important settings.

Step 2: First of all, you will need the IP address of the RTCM Base Station in your local network.
You have following options: either you discover the IP address by connecting to your network router (usually by typing http://192.168.1.1 or http://192.168.0.1 in your web browser), then look for a device named “ANavS-RTCM-Station”, or you use network discover software like nmap. More details on this can be found in the article Using the IP scanning-tool NMAP .

Step 3: If you want to access the ANavS® RTCM Base Station outside of the local network, the IP-address of you router is needed. The easiest way to do this is to call the page https://www.outsideopen.com/ip/ within your local network. The shown numbers are your public IP-Address.

Step 4: If your router is connected to the Internet, you can also access to your RTCM Base Station from outside your local network. To do so, you will need to configure your router first. You will have also to make your local network accessible from outside. In order to ensure your network is accessible from outside, you will need the external IP address of your router, i.e. the IP address for which the router is “seen” from the global Internet (assuming your router is connected to the Internet). This IP address is managed from your Internet Service Providers (ISP). Some ISPs do not provide you with a static IP address, but rather change it usually in a 24h time window. If this is the case, you will need to set up a Dynamic DNS service that keeps track of the external IP changes. Please refer to your network administrator to know the policy regarding your external IP address.

Step 5: Assuming you have your external IP address set up correctly, you also have to configure your router to enable port forwarding. Port forwarding maps requests coming from outside the network at a specific port number to a local IP address from within your local network at a second port number. Therefore, in other words, it redirects your traffic from outside to a specific device inside the local network.

The following example shows the rerouting of correction-data of the RTCM Base Station to an arbitrary Port of the router:

External IP address of the router

external port No.

Local IP address of the Pi

Internal port No.

82.135.2.37

2101

192.168.1.101

2101

In the upper example, you will have to configure the port forwarding to reroute the traffic coming from outside (landing so at the external IP of your router, namely 82.135.2.37) at port 2101 to the local IP of the RTCM Base Station (192.168.1.101) at port 2101. Note that choosing external port 2101 is arbitrary (is always best practice not to choose a port that is a well known port).
Having your router’s port forwarding set up as in the above example, to connect to your RTCM Base Station from outside the local network just configure your RTCM stream on the MSRTK Board with IP 82.135.2.37 and with port 2101. The traffic will be automatically rerouted to 192.168.1.101 at port 2101 in your local network.

HINT: The internal port number 2101 in this example must be the one which was defined of you in the calibration-process of the RTCM Base Station (see article Getting Started Guide: RTCM Base Station).
The external port number 2101 must be the one defined in the configuration of the MSRTK Board with the RTCM input stream address (see article Getting Started Guide: MSRTK Module).
Following an example for this:
RTCM_User:anavs123@:2101/ANAVS